ASTEROIDEA 77 



the other, Hoplaster Perrier,^ with the single species H. spinosus 

 Perrier, is known from the Bay of Biscay (49° 48' N., 15° 02' W., 

 2995-3307 m. (" Talisman "), and may therefore with great prob- 

 ability be expected to occur also nearer the British coasts. ^ 



Ver}^ probably Pentagonaster lepidus Sladen, from off the 

 Azores, 1800 m. (" Challenger "), also belongs to the Gnathas- 

 teridae. It bears a great resemblance to Odontaster mediterraneus, 

 but is stated to lack the recurved hyaline spine on the jaws. It 

 is only a 3"oung specimen (R = 7-5 mm.), probably a Hoplaster, 

 perhaps only the young H. spinosus (" Challenger'' Asteroidea, 

 p. 275, PI. LVII. 1-4). 



Key to the genera of Gnathasteridce known from or likely to occur 



in the British seas. 



A single large, hyaline, recurved spine on jaws ; covered with short, 



slender spinelets . . . . 1. Odontaster Verrill 



No large recurved, hyaline spine on jaws ; covered all over with 



long, slender, movable spines . . . Hoplaster Perrier 



1. Odontaster Verrill. 



Marginal plates large, forming a broad border around the disk, 

 Avhich is pentagonal or broadly stellate. Dorsal side with small, 

 slender spinelets, arranged more or less distinctly in the shape of 

 paxillse. One large recurved hyaline spine on jaws. Simple 

 pedicellarise may occur. 



One species known from the British (and N.E. Atlantic) seas. 



1. Odontaster mediterraneus MarenzeWer. (Figs. 42-43.) 



Body flat, arms short. The whole body covered with a dense 

 coat of slender spinelets, those of the oral side slightly longer. 

 Marginal plates diminishing gradually in size towards end of 

 arms. Furrow spines 3-4 ; on the outer side the adambulacral 



^ The position of the genus Hoplaster within the family Gnathasteridae 

 is not bej^ond doubt, because of its lacking the large, recurved spine on the 

 jaws, otherwise so characteristic of the family. The general appearance 

 and the presence of a large, odd interradial marginal plate, however, would 

 seem to indicate its near relationship to Odontaster. 



- Perhaps this locality might with equal right be reckoned in the 

 British area and the species therefore included in the British Fauna. Since, 

 however, the matter is questionable, and as the author has never seen a 

 specimen of this form, and therefore could only quote the description given 

 by Perrier {Echinodermes du " Travailleur'' et du "Talisman'", p. 324, 

 PI. XIV. 2), it has been thought sufficient to give in the key the main char- 

 acters by which this sea-star can at once be recognised, and otherwise only 

 refer to Perrier's description. 



